GREENE: Millions of consumers - maybe including you - went online yesterday searching for deals on Cyber Monday. This is the biggest e-commerce shopping day. Online sales for the day hit $2 billion. That's up nearly 20 percent over last year.

NPR's Sonari Glinton reports.

SONARI GLINTON, BYLINE: For all the hype of last week's pre- and post-Thanksgiving sales, you know, people camping to get deals, the real story has been phones and tablets.

JAY HENDERSON: I think mobile's really reached a tipping point.

GLINTON: Jay Henderson is with IBM's Smarter Commerce. He says mobile traffic is 60 percent of all online line traffic and sales from mobile devices represent about a quarter of online sales.

There's more devices for retailers to support, you know, smartphones and tablets, you know, along with trying to bring some of the best of online shopping into the stores.

According to the National Retail Federation, millions more people showed up to stores over the last few days but they bought less; sales were down about three percent for Black Friday. At the same time, sales on mobile devices increased over the last year. Consumers are increasingly looking for bargains on the Monday after Thanksgiving.

HENDERSON: Retailers are certainly helping encourage that by holding back some promotions as well as designing new promotions just for Cyber Monday. And so, you know, I think where we find ourselves is that, you know, it continues to be a really strong shopping day.

GLINTON: Henderson says people will still go out on Black Friday next year, but he expects them to spend more money on their mobile devices on Cyber Monday.